1. Field of the Invention
The present invention relates to a touch panel, and more particularly, to a touch panel including an optical compensation layer to improve an appearance quality of the touch panel.
2. Description of the Prior Art
In recent years, touch sensing technologies have developed flourishingly, and electronic products, such as mobile phones, tablet PCs, GPS navigator systems, laptop PCs, and desktop PCs, which have both the touch sensing function and the display function, are commercialized accordingly. There are many diverse technologies of touch panel, such as the resistance touch technology, the capacitive touch technology and the optical touch technology which are the main touch technologies in use. The capacitive touch technology has become the mainstream touch technology for the high-end and the mid-end consumer electronics, because the capacitive touch panel has advantages such as high precision, multi-touch property, better endurance, and higher touch resolution.
In the capacitive touch technology, transparent sensing electrodes are used to detect the variations of electrical capacitances around a touch point, and feedback signals are transmitted via connecting lines, which interconnect all of the transparent sensing electrodes along different axis directions to locate the touch points. In the conventional capacitive touch technology, the transparent sensing electrodes are made of transparent conductive materials such as indium tin oxide (ITO) which is a material with a high refractive index (about 1.7 to 2.0) but still may absorb some light. Therefore, a visual difference may be generated between a region with the transparent sensing electrodes and a region without the transparent sensing electrodes, an issue of visible transparent sensing electrodes may occur, and an appearance quality of the touch panel may accordingly be affected. In addition, the issue of visible transparent sensing electrodes may become more serious in large size touch panels because a thickness of the transparent sensing electrode has to be thicker to lower the total resistance for the driving requirement. For example, when a size of the normal touch panel is larger than 7 inches, the thickness of the transparent sensing electrode may have to be thicker than 90 nanometers to lower the total resistance, and the issue of visible transparent sensing electrodes may become more serious. In the conventional capacitive touch panel, a silicon oxide layer or an organic photo resist layer are generally used to cover the transparent sensing electrode. Since a refraction index of the silicon oxide layer or the organic photo resist layer of about 1.5 is apparently different from the refraction index of ITO, the silicon oxide layer or the organic photo resist layer may only be employed to protect or insulate the transparent sensing electrode from other things, and the issue of visible transparent sensing electrodes may not be improved with the silicon oxide layer or the organic photo resist layer.